Quickest way to do an If val1 = val2 with Word variables

[bcd]

Hi There all,

I am working on a program that has an interrupt routine that need to do a very fast "if val1 = val2 then", but it seems to be taking a long time for the if..then to evaluate. Based on my measurements it is taking 60uS.

Yes I said 60uS ! This is a 16f1936 running at 32MHz. Problem is that I am in a serial interrupt routine where each character is only 36uS, so I need to see if I am at the chosen channel and if so to load it into a buffer.

I have the buffer code and it works as is, but at higher refresh rates I am loosing data and it looks like I am overflowing the buffers in the uart.

What I really want to know is taking hints from this thread : http://www.picbasic.co.uk/forum/showthread.php?t=12635
is there an easier way to compare word1 to word 2 and to do something if they are equal ??

Driving me mad !!

bill

[Darrel Taylor]

val1 VAR WORD
val2 VAR WORD

SLOW

IF val1 = val2 THEN SomeWhere

FASTer

IF val1.HighByte = val2.HighByte THEN
    IF val1.LowByte = val2.LowByte THEN
        GOTO SomeWhere
    ENDIF
ENDIF

[bcd]

Hi Darrel,

Nope - same time. 60uS.
Think something weird might be going on here - might do some bare bones code.

bill.

[Acetronics2]

Hi, Bill

could you provide the "Guilty" interrupt code ???

easier to talk about real matter ...

Alain

PS: http://www.picbasic.co.uk/forum/show...3&postcount=13 ... obviously raises some questions !!!

[Phil Moore]

Hi Bill,

How about:

if (A XORNOT B) then something

XORNOT is a logical comparison testing for equality basically...

Phil.

[bcd]

Interesting thoughts.
I think its time to do some bare bones code to see which works out to be quicker.

Bill.